1. Field of the Invention
The present invention relates to a thrust plate subassembly, in particular for a motor vehicle friction clutch with automatic wear compensation comprising a housing which is fixable or fixed to a flywheel for joint rotation about an axis of rotation, a pressure plate arranged essentially fixedly in terms of rotation in the housing and axially displaceable relative to the latter, a force accumulator, preferably diaphragm spring, which is supported on the housing, on the one hand, and on the pressure plate, on the other hand, and presses the pressure plate in the direction of a side of the housing which is provided for connection to the flywheel, a wear-adjusting device arranged in the support path of the force accumulator between the force accumulator and one component of housing and pressure plate and having at least one adjusting element displaceable for wear compensation and prestressed in a wear-adjusting direction, and at least one play indicator arrangement for detecting a wear of friction linings of a clutch disk clampable or clamped between the pressure plate and the flywheel, the play indicator arrangement comprising: a blocking/detection element which is mounted on the one component and which is prestressed with a blocking portion against the wear-adjusting device and acts upon the latter, in order to prevent a movement of the at least one wear-adjusting element in the wear-adjusting direction, and a detection portion of which is in or is capable of being brought into interaction with another component or subassembly displaceable relative to the one component on the occurrence of wear, for the purpose of detecting the wear, on the occurrence of wear the blocking/detection element being capable of being brought, as a result of the interaction with the other component or subassembly, into a position for releasing the at least one adjusting element for the purpose of movement in the wear-adjusting direction.
2. Discussion of the Prior Art
The prior art discloses a thrust plate arrangement constructed in this way, in which the play indicator arrangement is designed as follows: an axial passage orifice is provided in the pressure plate through which a pinlike detection portion of a play indicator passes. The pinlike detection portion is slightly tiltable in the passage orifice. Attached firmly to that end of the pinlike detection portion which is located at a distance from the flywheel is a leaf spring element which extends in the direction of the wear-adjusting device, so that the wear-adjusting device is clamped between the pressure plate and the leaf spring element. By the leaf spring element being supported on the wear-adjusting device, due to the spring elasticity of said leaf spring element, the pinlike detection portion is tilted in its passage orifice and thus prestressed into a frictional clamping fit. When a wear of friction linings of a clutch disk which are located between the pressure plate and flywheel occurs, the pressure plate moves in the direction of the flywheel, until the pinlike detection portion stands up on the flywheel. At the same time, the detection portion is shifted axially in its passage orifice relative to the pressure plate counter to the prestressing action and the frictional clamping fit. That is to say, the end of the detection portion by which the latter is connected to the leaf spring element is also pushed away by the pressure plate, so that the prestressing force with which the leaf spring element acts upon the wear-adjusting device decreases. If, in a subsequent clutch disengagement operation, the action of the force of the diaphragm spring on the wear-adjusting device is reduced or released, the at least one adjusting element can move in the wear-adjusting direction, along with an increasing tension of the leaf spring element, until the prestressing force with which the at least one wear-adjusting element is prestressed in the wear-adjusting direction and the active force provided by the leaf spring element compensate one another and further movement of the at least one wear-adjusting element in the wear-adjusting direction is blocked by the leaf spring element. That is to say, in this arrangement, the play indicator, formed from the pinlike detection portion and the leaf spring element, is shifted increasingly relative to the pressure plate, and successive detensioning of the leaf spring element (during wear detection) and tensioning of the leaf spring element (during wear compensation) occurs.
In order, in an arrangement of this type, to carry out wear compensation to an extent which corresponds exactly to the wear of the friction linings which is detected by the play indicator, the spring elasticity or spring constant of the leaf spring element must be provided with the highest possible accuracy. If the leaf spring element is somewhat too soft, there is the risk that wear overcompensation will take place, and, if the leaf spring element is too rigid, there is the risk that the wear will not be sufficiently compensated for and that the interaction of the various components cannot take place in the intended way.
The object of the present invention is, therefore, to provide a thrust plate subassembly which, while being of simple design, can carry out accurate wear compensation automatically.
This object is achieved, according to the invention, by means of a thrust plate subassembly, in particular for a motor vehicle friction clutch with automatic wear compensation, comprising a housing which is fixable or fixed to a flywheel for joint rotation about an axis of rotation. A pressure plate is arranged essentially fixedly in terms of rotation in the housing and is axially displaceable relative to the housing. A force accumulator, preferably a diaphragm spring, is supported on the housing, on the one hand, and on the pressure plate, on the other hand, and presses the pressure plate in the direction of a side of the housing which is provided for connection to the flywheel. A wear-adjusting device is arranged in the support path of the force accumulator between the force accumulator and one component of the housing and the pressure plate and has at least one adjusting element displaceable for wear compensation and is prestressed in a wear-adjusting direction. At least one play indicator arrangement is provided for detecting wear of the friction linings of a clutch disk clampable or clamped between the pressure plate and the flywheel. The play indicator arrangement comprises a blocking/detection element which is mounted on the one component and which is prestressed with a blocking portion against the wear-adjusting device and acts upon the wear-adjusting device, in order to prevent a movement of the at least one wear-adjusting element in the wear-adjusting direction. A detection portion is in or is capable of being brought into interaction with another component or subassembly displaceable relative to the one component on the occurrence of wear, for the purpose of detecting the wear. Upon the occurrence of wear the blocking/detection element is capable of being brought, as a result of the interaction with the other component or subassembly, into a position for releasing the at least one adjusting element for the purpose of movement in the wear-adjusting direction.
In the thrust plate subassembly according to the invention, there is provided, furthermore, a detaining element, by means of which, when the blocking/detection element is brought into its position for releasing the at least one adjusting element, the blocking/detection element is capable of being detained against movement in its prestressing direction.
The construction according to the invention of the thrust plate subassembly allows operation on the following functional principle: on the occurrence of wear, the blocking/detection element is first brought, as a result of interaction of the detection portion with the other component or subassembly, into a position in which it does not act upon the wear-adjusting device, and therefore the at least one adjusting element is released for movement in the wear-adjusting direction. With the clutch engaged, however, the wear-adjusting device, and therefore also the at least one adjusting element, is initially still acted upon by the diaphragm spring and therefore cannot carry out a compensating movement. This is possible only during a subsequent clutch disengagement operation, during which the wear-adjusting device is released by the diaphragm spring. However, since, during a clutch disengagement operation of this kind, a movement generally occurs between one component and the other, which will result in the blocking/detection element being moved out of the position described above, the detaining element is provided, which now provides detention for the blocking/detection element and ensures that an interspace produced between the wear-adjusting device and the blocking portion as a result of interaction of the detection portion with the other component is filled again due to the fact that the at least one adjusting element moves in the wear-adjusting direction, not due to the fact that the blocking/detection element moves back into its initial position again.
In a construction of this kind, it becomes possible for the blocking/detection element to be designed, in terms of the prestressing force provided for it, so that in every operating state, that is to say every state of wear, this force is always sufficient to prevent unintended wear compensation in the event of action taken on the wear-adjusting device. That is to say, the blocking/detection element may, in principle, be prestressed against the wear-compensating device with a force which is markedly higher than that force by which the at least one wear-adjusting element is prestressed for the purpose of movement in the wear-adjusting direction. This becomes possible since the provision of the detaining element avoids the need to ensure a force equilibrium between these two forces.
In the thrust plate subassembly according to the invention, there is preferably provision for the blocking/detection element to be mounted essentially fixedly in one end region on the one component and to be prestressed by spring force against the at least one adjusting element.
An extremely simple construction with a reliable effect can be obtained if the blocking/detection element is a spring element, preferably a leaf spring element.
So that a reliable operation of the detaining element can be provided, in one embodiment of the invention the detaining element is prestressed in a direction for detaining the blocking/detection element.
For example, the detaining element may be of essentially wedgelike design and may be supported with a first wedge face on the one component and detain the blocking/detection element with a second wedge face.
Alternatively, there may be provision for the detaining element to comprise a catch element with catch projections, preferably a sawtooth-shaped toothing, which prevents a movement of the blocking/detection element in its prestressing direction and allows a movement opposite to the prestressing direction.
A construction which can be produced in a particularly simple way is obtained if the one component comprises the pressure plate. In this case, the other component preferably comprises the housing.
In an embodiment of this kind, the housing may then have provided on it an interaction portion, against which the detection portion of the blocking/detection element can come to bear when wear occurs.
In the thrust plate subassembly according to the invention, the number of parts can be kept small if the interaction portion is formed by a surface region of the housing.
Alternatively, however, it is possible for the housing to have mounted on it an interaction element which has an interaction portion.
An embodiment of this kind is particularly preferred, since it can be used at the same time for providing transport protection. Transport protection is intended, within the meaning of the present invention, to refer to protection against unintentional wear compensation taking place during the transport of the thrust plate subassembly according to the invention, that is to say before the latter is assembled together with a flywheel or other components. For this purpose, for example, the interaction element may be capable of being arranged on the housing in a first position, in which the interaction portion cannot come into interaction with the detection portion, and of being arranged in a second position, in which the interaction portion can come into interaction with the detection portion.
In a further alternative embodiment, the other component may comprise the flywheel.
In order to ensure, for example when maintenance work is carried out or during transport, before the thrust plate subassembly is connected to a flywheel or the like, that an excessive shift of the blocking/detection element subsequently leads to a correspondingly large wear-compensating movement, it is proposed, furthermore, that a maximum regulating-travel limiting arrangement be provided for the detaining element.
In this case, the maximum regulating-travel limiting arrangement may comprise a blocking element, preferably a blocking projection, on the detaining element and a counterblocking element, preferably a blocking recess, on the at least one wear-adjusting element.
In one embodiment of the thrust plate subassembly according to the invention, there may be provision for arranging the blocking/detection element so as to extend essentially radially.
For example, the blocking/detection element may be mounted with a radially inner region on the one component, and the detection portion and/or the blocking portion may be provided in a radially outer region of the blocking/detection element.
In an alternative embodiment, there may be provision for arranging the blocking/detection element so as to extend essentially in the circumferential direction. Particularly when a blocking/detection element is used which is composed of spring material and has to have a specific minimum length in order to allow it to execute a sufficient deformation travel. The advantage of a configuration of this kind is that less radial construction space is taken up, so that, when a pressure plate forms the one component, the central orifice in the latter can be larger, for example so that a clutch disk together with a torsional vibration damper or the like can be used.
In an embodiment of this type, there may be provision for the blocking/detection element to be mounted in a first circumferential end region on the one component and to have the detection portion and/or the blocking portion in a second circumferential end region.
The blocking/detection element may have a basic body portion which extends essentially in the circumferential direction and from which the detection portion and/or the blocking portion project/projects essentially radially in the second circumferential end region.
In order, furthermore, to prevent the blocking/detection element from rotating relative to that component on which it is mounted, a rotation securing arrangement may also be provided, for securing the blocking/detection element against rotation relative to the one component.
The rotation securing arrangement may comprise, for example, a securing portion which is provided on one end region of the blocking/detection element and which interacts with a countersecuring portion on the one component.
In friction clutches in which, as described above, the compensation of wear occurring in the region of the friction linings of the clutch disk can be carried out automatically by means of the displacement of any components of a wear-adjusting device, there is basically the problem that, when, for example after the friction linings have been worn away completely, the clutch disk is replaced by a new clutch disk with unworn friction linings, various components in the region of the wear-adjusting device are not in a position which corresponds to such a new unworn state of the friction linings. This may present the problem that the force accumulator, that is to say, for example, a diaphragm spring, may not work in the desired position range during subsequent operation and there is therefore a correspondingly undesirable spring characteristic. In order to counteract this problem, according to a further aspect of the present invention, a thrust plate subassembly, in particular for a motor vehicle friction clutch with automatic wear compensation, is proposed, which comprises:
a housing which is fixable or fixed to a flywheel for joint rotation about an axis of rotation,
a pressure plate arranged essentially fixedly in terms of rotation in the housing and displaceable axially relative to the housing,
a force accumulator, preferably a diaphragm spring, which is supported on the housing, on the one hand, and on the pressure plate, on the other hand, and presses the pressure plate in the direction of a side of the housing which is provided for connection to the flywheel,
a wear-adjusting device arranged in the support path of the force accumulator between the force accumulator and one component of the housing and the pressure plate and having at least one adjusting element displaceable for wear compensation and prestressed in a wear-adjusting direction, and
at least one play indicator arrangement for detecting wear of friction linings of a clutch disk clampable or clamped between the pressure plate and the flywheel.
This thrust plate subassembly has, furthermore, a resetting arrangement, by means of which the wear-adjusting device is capable of being brought into a position which corresponds to a state of lower wear.
It is thereby possible to ensure that, when the entire clutch or thrust plate subassembly is restored to a state of lower wear, for example due to the replacement of a clutch disk, the wear-adjusting device is correspondingly also put into an associated state which the wear-adjusting device assumes when the wear-relevant variable likewise has lower or no wear.
For this purpose, there may, for example, be provision for the at least one adjusting element to be capable of being brought by means of the resetting arrangement out of an initial position in a resetting direction into a position which corresponds to a state of lower wear than the initial position. Furthermore, the initial position may be a wear position which the at least one adjusting element assumes when the maximum possible wear is present, or it may be a position in the region of this wear position.
Moreover, there may be provision for the at least one adjusting element to be capable of being brought by means of the resetting arrangement into a wear-free position which the adjusting element assumes when there is no or essentially no wear. In order in a simple way to bring about resetting into a state corresponding to lower wear, the resetting arrangement may comprise at least one driving element which is capable of being set in movement by a driving member, preferably a driving tool, and the movement of which is capable of being converted into a resetting movement of the at least one adjusting element.
The interaction between the driving element and the at least one adjusting element may take place in that the at least one adjusting element has an engagement formation, preferably a toothing, which is in driving contact with a counterengagement formation, preferably a toothing, on the at least one driving element.
In a construction which acts in a particularly simple way, the at least one adjusting element comprises an adjusting ring which has a toothing at least in the region of the at least one driving element, and the at least one driving element comprises a driving gearwheel meshing with the toothing of the adjusting ring.
The at least one driving element is preferably carried on the one component.
So that resetting can also be carried out when the thrust plate subassembly is in the assembled state, it is proposed that the at least one driving element has a tool engagement formation accessible preferably from outside the thrust plate subassembly.
Furthermore, in the thrust plate subassembly according to the invention, there is preferably provision for the play indicator arrangement to comprise a blocking/detection element which is mounted on the one component and which is prestressed with a blocking portion against the wear-adjusting device and acts upon the latter, in order to prevent a movement of the at least one wear-adjusting element in the wear-adjusting direction. A detection portion of the detection element is in or is capable of being brought into interaction with another component or subassembly displaceable relative to the one component. Upon the occurrence of wear, for the purpose of detecting the wear, on the occurrence of wear the blocking/detection element is capable of being brought, as a result of the interaction with the other component, into a position for releasing the at least one adjusting element for the purpose of movement in the wear-adjusting direction, Furthermore, a detaining element is provided by means of which, when the blocking/detection element is brought into its position for releasing the at least one adjusting element, the blocking/detection element is capable of being detained against movement in its prestressing direction.
In a construction of this kind, furthermore, by means of the resetting arrangement, the detaining element is then capable of being brought preferably into a position of the latter which is assigned essentially to that position of the wear-adjusting device which the latter assumes after a resetting operation has been carried out.
This may be implemented, for example, in that, during the movement of the at least one adjusting element in the resetting direction, the detaining element is capable of being moved by means of the at least one adjusting element.
So that a simple construction as possible can be provided here, it is proposed that the at least one adjusting element or the detaining element has a take-up projection which engages with movement play in the adjusting direction or the resetting direction into a take-up recess of the other element in each case.
Furthermore, in the thrust plate according to the invention, there is preferably provision for the at least one play indicator arrangement to be capable of being brought by means of the resetting arrangement into a position which corresponds to a state of lower wear. This may be implemented in a simple way, for example, in that, by means of the resetting arrangement, the detention of the blocking/detection element against movement in its prestressing direction is capable of being canceled.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.